{{ site_name }} is returning host name instead of site name

In customizing the Wagtail login page, I set up the following using {{ site_name }} as documented:

{% extends "wagtailadmin/login.html" %}
{% block branding_login %}Sign in to {{ site_name }}'s CMS{% endblock %}

I expected (and wanted) to see the site name on the login page, but instead it renders the host name. Is this how it is supposed to behave?

Technical details

• Python version: 3.6
• Django version: 2.1.4
• Wagtail version: 2.4
• Browser version: Chrome 71

[gasman]

@allcaps If there’s evidence that people are being persistently confused by these variables, then we should look at ways to prevent that - but I don’t think we can judge that based on one report.

I can’t think of any scenario where removing these variables would break anyone’s site, but I can’t rule out that possibility entirely - which means we’re stuck weighing up that probability against the probability that making the change will prevent someone in future from falling into this trap. Faced with those alternatives, I’d rather keep things as they are, so that we don’t risk breaking things for the user who is following the spec accurately.

[allcaps]

@gasman Thank you for the thorough explanation and example.

I’m fine that Wagtail doesn’t want to make assumptions about multitenant systems.

There is still a small issue: Wagtail uses Django’s auth_views.LoginView. This Django view provides context containing site and site_name. But the values are looked-up in the Django way. They fall back to the domain name. The default login template doesn’t use these context variables.

I’m not surprised that integrators assume that site and site_name context is the current Wagtail site and available for convenience. They only get the current domain name. That is not the expected behaviour.

Should the site and site_name variables be removed from the login view context? Or are these redundant context variables something we can live with?

I do understand the desire to display the current site name on a login page. The user is about to submit credentials and needs to know he is in the right place. Multitenant or single site setup, the requirement stays the same.

The fact that the view provides misleading context is a bug imho.